Can Variables Be Capital Letters?
Date: 09/19/2006 at 10:32:15 From: Annie Subject: Naming variables I have a friend who was marked down for using capital letters for variables--3A. The teacher said it must be a lower case letter--3a. I can't find a hard and fast rule about this anywhere. My question is, is it a rule or is it what people usually do?
Date: 09/19/2006 at 12:28:44 From: Doctor Peterson Subject: Re: Naming variables Hi, Annie. There is no rule that you can't use a capital letter as a variable; it is done all the time, though certainly less often than lower case. For example, the area of a trapezoid is sometimes written as A = (B + b)h/2 where A is the area, B is one base and b is the other, and h is the height. There IS a rule, however, that once a variable is defined, you should not change the case. Often students prefer writing capital letters, and will change a variable r in a problem to R in their answer. This should be discouraged, as you can see from my example above: B and b are different things, and if you habitually write b as B, you will mess up the formula badly! I would never mark an answer wrong if the student chose a capital letter for himself; I might call it wrong if he changed the case of a variable that was given in a problem, especially if there were mixed cases given. If you have any further questions, feel free to write back. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/
Date: 09/23/2006 at 00:40:14 From: Annie Subject: Thank you (Naming variables) Thanks so much for the help. You answered my question completely and I really appreciate your quick response. It is great to know I can get my questions answered when I have them. Thanks again! Annie
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.